Heart valves, such as the aortic valve, are sometimes damaged by diseases or by aging which can cause problems with the proper function of the valve. Heart valve disease generally takes one of two forms: stenosis, in which a valve does not open completely or the opening is too small, resulting in restricted blood flow; or insufficiency, in which blood leaks retrograde across the valve that should be closed. Valve replacement may be required in severe cases to restore cardiac function. In common practice, replacement requires open-heart surgery with its attendant risks, expense, and extended recovery time. Open-heart surgery also requires cardiopulmonary bypass with risk of thrombosis, stroke, and infarction.
Catheter based valve replacement has been proposed as a way to effect valve replacement percutaneously and to avoid open-heart surgery. Such procedures involve excision of the native valve and replacement of the native valve with a prosthetic valve, or installation of a prosthetic valve over the native valve. To avoid cardiopulmonary bypass, the catheter based valve replacement is performed on a beating heart. Following excision of the native valve, no valve is present to preserve the pumping action of the heart while the permanent prosthetic valve is being implanted.
An additional consideration in both open-heart and catheter based valve replacement is the healing process after the prosthetic valve is implanted. After the valve replacement procedure, scar tissue must form around the sewing cuff to secure the prosthetic valve in position. In current practice, multiple knotted sutures anchor the prosthetic valve in place until ingrowth of scar tissue into the sewing cuff takes over the load bearing function. However, the placement of knotted sutures by catheter can be very difficult and time consuming.
Artificial heart valves for temporary use are known in the art, but present certain problems. Some designs are complex, inflating and deflating balloons to alternately block and permit flow. Such designs require complex sensing and control systems. Other designs fail to provide access for tools that must reach the valve site for removal of the native valve and placement of the prosthetic valve. Yet other designs require elaborate supporting frames to hold the valve portion.
U.S. Pat. No. 3,671,979 to Moulopoulos discloses an artificial heart valve for implantation in close proximity to a malfunctioning or damaged natural aortic or mitral heart valve by remote means without performing an open chest or other major surgical operation, the artificial heart valve comprising a flexible membrane in the form of an umbrella.
U.S. Pat. No. 4,056,854 to Boretos et al. discloses an artificial valve remotely placeable in a blood vessel without major surgery to supplant the function of a malfunctioning natural valve including an expansible check valve remotely placed in a constricted configuration through the vessel and a remotely removable constraint for selective expansion of the check valve for sealing engagement thereof within the walls of the vessel at the desired location.
U.S. Pat. No. 4,705,507 to Boyles discloses an arterial catheter of the multi-lumen type having an inflatable balloon portion to wedge the catheter in place against the arterial wall. Multi-infusions are allowed through the segmented multi-lumens. The catheter is designed to allow blood to flow in the arterial system with the catheter in place. During diastolic phases, the blood flow will be closed off with movable plastic valves.
U.S. patent application No. 20020151970 to Garrison et al. discloses a valve implantation system having a valve displacer for displacing and holding the native valve leaflets open wherein a replacement valve may be attached to the valve displacer before or after introduction and may be positioned independent of the valve displacer and wherein a temporary valve mechanism may be used to provide temporary valve functions during and after deployment of the valve displacer.
WIPO International Publication No. WO 00/44313 to Lambrecht et al. discloses temporary valve devices with one or more cannulae which guide insertion of the valve into the aorta. The valve devices expand in the aorta to occupy the entire flow path of the vessel. In one embodiment, the temporary valve has leaflets which act in concert to alternately block or allow blood flow.
It would be desirable to have a percutaneously delivered temporary valve that would overcome the above disadvantages.